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Abstract #2057

Steady State Free Precession (SSFP) and FMRI: Expressions Accounting for Reversible Vs Irreversible Transverse Relaxation Effects

Robert V. Mulkern1, Mukund Balasubramanian1, Dimitrios Mitsouras2, Stephen Haker2

1Department of Radiology, Children's Hospital Boston, Boston, MA, United States; 2Department of Radiology, Brigham and Women's Hospital, Boston, MA, United States

Reversible relaxation processes resulting from inherent frequency distributions have been incorporated into SSFP signal analyses to separately examine how changes in either reversible or irreversible transverse relaxation affect SSFP based fMRI signal intensities. The analytic expressions obtained for Lorentzian, Gaussian and square distributions were derived using a single sum series expansion previously unnoted which allowed for a closed form solution for the Lorentzian and rapidly converging solutions for Gaussian and square distributions. The expressions should be useful for allowing detailed investigations of mechanisms affecting SSFP based fMRI studies in either transition band or passband modes.